keypad_arduino

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#include <Keypad.h>
#define BINTANG 42
#define PAGAR 35
#define TOMBOL_A 65
#define TOMBOL_B 66
#define TOMBOL_C 67
#define TOMBOL_D 68

const byte ROWS = 4; //four rows const
const byte COLS = 4; //three columns

char keys[ROWS][COLS] = {
  {1, 2, 3, 'A'},
  {4, 5, 6, 'B'},
  {7, 8, 9, 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {7, 6, 5, 4}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {3, 2, 1, 0}; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

long dtKey = 0;

void setup() {
  //Serial.begin(9600);
  lcd.init();
  lcd.backlight();
}
void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == BINTANG ) { // clear data = tekan *;
      lcd.clear();
      dtKey = 0;
      key = 0;
      lcd.print(dtKey);
    }
    if ( key == 48 )key = 0; // conversi variable '0' ke 0
    lcd.clear();
    dtKey = dtKey * 10 + key;
    lcd.print(dtKey);
  }
}